Subject underpotential deposition

Although not the subject of this article, double layer studies are briefly discussed in this paragraph in order to demonstrate that ex situ XPS studies indeed provide information about the state of the electrode exposed to an electrochemical environment at a defined potential. A crucial step in any ex situ experiment is the emersion of the electrode. Here the question arises whether the electrochemical double layer or part of it is preserved at the interface after emersion and transfer. Winograd et al. [10,11] first demonstrated that the electrode under UHV conditions still remembers the electrode potential applied at the time of emersion. These authors investigated oxide formation on Pt and the underpotential deposition of Cu and Ag on Pt by means of XPS and proved that the electrochemically formed oxide layer and... 

An ex situ EXAFS study was conducted for Cu underpotential deposition on polycrystalline Pt in 0.2mM CUSO4 + 0.5M H2SO4. The iodine-treated Pt was subjected to Cu underpotential deposition, the features of which were observed by EXAFS. ° An EXAFS study of Cu... 

The occurrence of underpotential deposition of various metals on different metal substrates is an interesting subject Why is it possible The relation of the underpotential deposition shift potential was plotted... 

Electrodes modified by underpotential deposition of metal were subjected as electrocatalysts to reduction of oxygen,oxidation of formic acid, and other processes in which polycrystalline metal substrates were used (see review in Ref. 151). Electrocatalysis of single-crystal electrodes modified by underpotential deposition was also investigated, as reviewed by Ad2iC. ... 

One of the subjects that is still quite intensively developed (using electrochemical methods frequently combined with nonelectrochemical techniques) concerns reduction of Hg compounds at various surfaces (e.g. Pt or Au), with the emphasis laid on underpotential deposition (UPD) of mercury. Deposition of mercury on other metals is generally important for better understanding of the mechanism of the formation of amalgams. Moreover, underpotential Hg deposition characteristics constitute a significant source of information on Hg-metal interactions. In turn, mercury film electrodes obtained by such deposition have a significant appKcation in electrochemical analysis ofvarious species. 

Underpotential deposited layers have a strong effect on the electro-catalytic properties of electrodes for surface-sensitive reactions such as organic oxidations, hydrogen evolution, oxygen reduction, etc. A review on this subject has recently been published by Adzic [131a, b]. 

The adsorption of anions such as halides, cyanide, and sulfate/bisulfate on electrode surfaces is currently one of the most important subjects in electrochemistry [1 - 3]. It is well known that various electrochemical surface processes such as underpotential deposition of hydrogen and metal ions are strongly affected by co-adsorbed anions. Particularly, structures of the iodine adlayers on Pt, Rh, Pd, Au, and Ag surfaces have... 

Underpotential deposition Underpotential deposition (upd) occurs when monolayers (or submonolayers) of a metal ad-atom are deposited on a foreign metal substrate at potentials positive of the reversible Nernst potential for bulk deposition [16]. Monolayers will only form when a low work function metal is deposited onto the surface of a higher work function substrate. In this case, the metal ad-atom-substrate bond is greater than the ad-atom-ad-atom bond formed in bulk metal deposition. Upd phenomena have been the subject of extensive work using SPMs and of particular interest is the role of coadsorbed anions on this process, as a function of electrode potential. 

Underpotential deposition (UPD) of foreign metal adatoms on platinum single crystals in different acid electrolytes occupies a special position in interfacial electrochemistry. Of various systems examined the underpotential deposition of Cu on a Pt(lll) surface has been of particular interest since the interpretation of the nature of the Pt(lll)-Cu-Anion structure have been the subject of considerable controversy. Overviews with some different perspectives can be find in the References. [J-I3]. 

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